Canberrans with respiratory illnesses such as asthma are being advised to stay indoors and avoid strenuous activity until the dust settles.

The hot conditions and strong winds fanned a bush fire east of Potters Hill, on the ACT/NSW border.

(9NEWS) (9NEWS)

The out-of-control blaze has burnt through 100 hectares of bushland, with fire crews battling throughout the night to bring the fire under control.

Meanwhile, Victorians remain on high alert tonight with more than 50 fires burning across the state. Hundreds of beef and dairy cattle, as well as farm buildings, have also been destroyed, and 40,000 hectares of land burnt.

New South Wales has also faced unseasonably hot conditions, with temperatures in the high 30s and 40s fanning an out-of-control bushfire near Bega.